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Diversity of species assemblages of islands: Predictions and their test using tree species composition of shola fragments
No full textBased on all possible combinations of species that can theoretically exist on islands of different sizes, we estimated similarities among islands of equal size in their species compositions. We found that similarity coefficients among islands of equal sizes increases and the coefficients of variation for similarities decreases with increase in the size of islands. Accordingly, it can be predicted that the species compositions of small fragments shall be more diverse compared to large fragments. We tested this prediction using the tree species composition of the shola fragments at BR Hills, Western Ghats. Similarities among sholas were measured as coefficients of correlation between the frequencies of species in them and also as proportions of species shared among sholas. Small sholas were less similar and shared fewer species among themselves, compared to medium and large sholas. Also, small sholas showed higher coefficient of variation for the correlation coefficients and for proportion of species shared than medium or large sholas. In other words, species assemblage diversity among sholas was found to decrease with their size and large islands appeared to converge towards a common assemblage of species. Based on our results, we argue that small fragments add structural and functional heterogeneity to the ecosystem and hence are as important as are the large fragments in conserving biodiversity
Applications of geographic information systems, remote-sensing, and a landscape ecology approach to biodiversity conservation in the Western Ghats
Full text linkThe mountains along the west coast of peninsular India, the Western Ghats, constitute one of the unique biological regions of the world. Rapidly occurring
land-cover and land-use change in the Western Ghats has serious implications for the biodiversity of the region. Both landscape changes as well as the distribution of biodiversity are phenomena with strong spatial correlates. Recent developments in remote-sensing technology and Geographic Information Systems (GIS) allow the use of a landscape ecology and spatial analysis approach to the problem of deforestation and biodiversity conservation in the Western Ghats. Applications of this
approach include analyses of land-cover and landuse change; estimation of deforestation rates and rates of forest fragmentation; examination of the spatial correlates of forest loss and the socioeconomic
drivers of land-use change; modelling of deforestation;
analysis of the consequences of land-cover and land-use change in the form of climate change and change in distribution of biodiversity; biomass estimation;gap analysis of the effectiveness of the protected area network in conserving areas of importance for biodiversity conservation; and conservation planning. We present examples from our work in the Western Ghats, in general, and in the Agastyamalai region and Biligiri Rangan Hills, in particular, as well as that of other researchers in India on various aspects of applications of GIS, remote sensing, and 'a landscape ecology approach to biodiversity conservation